Most of the reactions of solid materials in high temperature environments are controlled by crystal chemistry. In other words, chemical reactivity is determined by the crystal structure and defect structure of the solid materials in these aggressive media. In this paper, we shall discuss some corrosion reactions of solid materials that have gained considerable importance recently, in the field of high temperature corrosion, pointing out how solid state chemistry plays a role in this crucial branch of chemical engineering and technology. (c) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.